I've used four-inch barred feathers for over a decade, and hunted in downright blizzards, blinding rain storms, consistent downpours... you name it, I've had my feathers in it.

I've never worried about arrow flight with my feathers for a couple reasons: First and foremeost, because I have practiced in those conditions. I always have a field-point tipped arrow with me, and as usual I have picked out a leaf or something to shoot at and let one fly in all those conditions to see the variance in results; there have been none noticeable enough to change the appeal feathers hold for me. Secondly, I've seen high-speed video of feathers "snapping" full at the moment of the shot, instantly shaking the excess moisture off.

There's also a product out there called "No Sno" which does a great job of waterproofing feathers.